Dr. David Katz: New Year’s toast to your ketones

Whatever the reasons, ketogenic diets are the flavor of the week, and legions seem poised to toast 2017 goodbye and welcome 2018 with ketogenic Kool-Aid. I consider them dangerously misguided.

The historical case for ketogenesis — denying the body its customary fuel sources so that glucose is in short supply, and instead it metabolizes fat preferentially, and generates ketone bodies as fuel — resides in starvation. The body effectively turns to auto-digestion to sustain itself during a protracted fast. Fat and protein stores in the body are converted to fuel, and metabolism then does run on ketone bodies.

In this modern age of epidemic obesity and type 2 diabetes, starvation has acquired a patina of merit. During starvation, blood sugar falls. Blood insulin falls. Blood cholesterol falls. Blood pressure falls. Weight declines. None of these were desirable throughout most of humanity’s subsistence, but all cry out “benefit” in this era of disease-by-excess.

But, alas, starvation has its drawbacks, among them the tendency to be fatal. When the body auto-digests, it is somewhat indiscriminate, and proteins can be leached even from vital organs such as the heart. That can disrupt micro-architecture, which can in turn disrupt electrical signaling, and that can and does cause fatal dysrhythmias.

Starvation, then, is a dubious proposition — but the appeal of its metabolic advantages in modern context persists. This tension has propagated an on-going quest to secure the metabolic advantages of starvation without the pesky inconveniences of actually starving, and risking sudden cardiac death. The initial successful result of this effort was calorie restriction, or CR.

CR reduces calories to a level that imposes many of the effects of starvation. Most approaches to CR are, in fact, ketogenic despite being high in total carbohydrate from particularly nutrient-rich foods: notably vegetables, fruits, beans, and legumes. A primary principle of CR is to compensate for low-calorie intake with reliance on the most nutritious foods. CR is associated with certain liabilities, such as infertility, but appears to enhance longevity. But, CR involves something akin to “gentle starvation” every day, so there is a joke about it: maybe it makes you live forever, or maybe it just feels like forever!

This, then, is where the New-Age idea of ketogenic diets was incubated. The current hope is to have your CR benefits, but eat those calories, too. By restricting all carbohydrate sources, the body can be forced to run on ketone bodies even in the absence of semi-starvation.

The ketogenic diet idea makes the huge leap of faith that ketone bodies per se can confer health benefit. The work the idea is born from, however, establishes nothing of the sort. Starvation involves not just ketone bodies, but starvation — and is overall a very bad idea for the health-conscious. CR might be a good idea, at least for health-conscious masochists, but its benefits are decisively linked to low-intake of calories and high-intake of nutrient rich plant foods; ketone body generation just comes along for the ride.

What evidence is there that CR can be replaced with carbohydrate restriction; that nutrient-rich plant foods can be mostly or entirely displaced by meat — and the health or longevity benefits of CR, themselves less than entirely proven, replicated? To the best of my knowledge, in humans: none.

There are short-term studies of ketogenic diets showing the usual metabolic benefits attached to almost any diet replacing the prevailing state of ingestive anarchy with some kind of discipline: reduced blood sugar, blood cholesterol, blood pressure, and weight. But lest you think short-term improvements in these markers a good idea makes, consider these other “interventions” that do the same: a bout of cholera, a crack cocaine binge, or the advance of tuberculosis. The historical name for tuberculosis, “consumption,” connotes exactly such effects. Perhaps the currently popular approach to ketogenic diets is a case apart, but the burden is on those making the claim to prove it — not on the rest of us to disprove it.

As I write this, the proposed “Guiding Principles” for healthful eating in Canada have just been released. They are eminently sensible, current, and evidence-based; so naturally, they are under immediate attack, as was the comparably sensible 2015 report of the Dietary Guidelines Advisory Committee here in the U.S. before ever its ink was dry. The beef and dairy industries oppose the movement toward more whole-food, plant-predominant diets so decisively associated with better health outcomes for people and planet alike. They would be more than glad to toast 2017 on its way with ketogenic Kool-Aid.

The likelihood, however, that they are toasting to your good health in 2018, let alone that of the planet, is very remote indeed. I do so, wishing you a happy New Year, and the boon of prudent choices.